1,720,969 research outputs found
LEARNING AND BUCKET BRIGADE DYNAMICS IN CLASSIFIER SYSTEMS
No full textClassifier systems are rule-based adaptive systems whose learning capabilities emerge from processes of selection andcompetition within a population of rules (classifiers). These processes are ruled by the values of numerical variables whichmeasure the fitness of each rule. The system's adaptivity is ensured by a fitness reallocation mechanism (the bucket brigadealgorithm) and by genetic algorithms which are responsible for the internal dynamics of the system. In this paper we discussclassifier systems as dynamical systems, the main focus being on the asymptotic dynamics due to the bucket brigade,abstracting from the action of the genetics. This topic is discussed with reference to a specific task domain, in which the systemis used as a detector of statistical properties of periodic or fluctuating external environments. We also describe a majorconsequence of the genetics on the bucket brigade dynamics, namely the proliferation of individual rules into subpopulationsof equivalent classifiers; we then show that this can eventually lead to undesired stochastic behavior or to the destabilization ofcorrect solutions devised by the system
THEORY OF ACTIVATED REACTION PROCESSES: NONLINEAR COUPLING BETWEEN REACTIVE AND NON REACTIVE MODES
No full textDeviations from the Kramers preditions resulting from the couplmg between a reactive and a non-reactwe mode arestudied in both the low- and hi&-diction Iimits. It is alsO argued how this simple picture may provide a breakdown of theupper Iimit imposed on the relaxation rate by transdion state theory
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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